fix: samples/client/petstore/java/microprofile-rest-client-outer-enum/pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMFASTERXMLJACKSONCORE-15907551

Author: snyk-bot

samples/client/petstore/java/microprofile-rest-client-outer-enum/pom.xml

@@ -157,7 +157,7 @@
     <junit.version>5.10.2</junit.version>
     <logback.version>1.5.13</logback.version>
     <cxf.version>3.2.7</cxf.version>
-    <jackson.jaxrs.version>2.17.1</jackson.jaxrs.version>
+    <jackson.jaxrs.version>2.21.2</jackson.jaxrs.version>
     <jakarta.activation.version>1.2.2</jakarta.activation.version>
     <jakarta.annotation.version>1.3.5</jakarta.annotation.version>
     <jakarta.json.bind.version>1.0.2</jakarta.json.bind.version>